The complete nucleotide sequence of the AIDS (HIV) virus has been reported by several investigators. (See Lee Ratner et al., Nature 313, p. 277, January 1985; Muesing et al., Nature 313, p. 450, February 1985; and Wain-Habson et al., Cell 40, pp. 9-17, January 1985.) The envelope gene has been associated particularly with antigenicity and infectivity. However, the envelope portion is also known to have regions which are highly divergent. The HIV virus envelope glycoprotein has been shown to affix covalently to the brain membranes of humans, rats, and monkeys and to cells of the immune system.
The realization that viruses may exert cell and tissue tropism by attachment at highly specific sites on cell membrane receptors has encouraged investigators to seek agents which would bind at the viral receptor sites of cell membranes and thus prevent binding of a specific virus to these cells. A demonstration of specific receptor-mediated vaccinia virus infectivity being blocked by synthetic peptides has been previously demonstrated (Epstein et al., Nature 318: 663-667).
The HIV virus has been shown to bind to a surface molecule known as the CD4 or T4 region, which is present on various cells susceptable to HIV infection, including T lymphocytes and macrophages. (See Shaw et al., Science 226, pp. 1165-1171 for a discussion of tropism of HTLV-III.)
In addition to symptoms arising from immunodeficiency, patients with AIDS show neuropsychological defects. The central nervous and immune systems share a large number of specific cell-surface recognition molecules, serving as receptors for neuropeptide-mediated intercellular communication. The neuropeptides and their receptors show profound evolutionary stability, being highly conserved in largely unaltered form in unicellular organisms as well as higher animals. Furthermore, the central nervous and immune systems show common DC4 (T4) cell-surface recognition molecules which serve as receptors for the binding of HIV envelope glycoprotein (gp 120). Since the same highly conserved neuropeptide informational substances integrate immune and brain function through receptors remarkably similar to those of HIV, we postulated a very similar amino acid sequence between the HIV glycoprotein gp 120 and a short peptide previously identified in another context from the envelope region of the Epstein Barr-Virus might indicate the core peptide essential for viral receptor binding. It was postulated that such a peptide would be useful in preventing infection of cells with the HIV by binding with receptor cells and blocking the binding of HIV gp 120, that such peptides binding to the receptor cites would give rise to production of antibodies directed to the peptide sequence, and that these peptides might be used to provide immunological basis for prevention of AIDS.